It is difficult to achieve accurate acquisition of weak global positioning system( GPS) signals with traditional methods. A weak signal acquisition strategy based on block processing and differentially coherent( BPDC)...It is difficult to achieve accurate acquisition of weak global positioning system( GPS) signals with traditional methods. A weak signal acquisition strategy based on block processing and differentially coherent( BPDC) is put forward after analyzing the advantages and disadvantages of coherent and non-coherent integration algorithms. Code phase parallel search of the pre-coherent integration is conducted by using fast Fourier transform( FFT),and the results are then differential coherent processed and block processed. BPDC method reduces computation cost compared with coherent and noncoherent( CNC) algorithm. The performance of the two algorithms is also compared based on simulated signals. The result shows that the noise suppression effect of BPDC algorithms is superior to that of traditional CNC algorithm,and the superiority of BPDC is more apparent with the reduction of carrier to noise ratio( CNR). In the case that the pre-coherent integration length is 4 ms and CNR is reduced to 28 dB-Hz,CNC algorithm cannot yet acquire signal correctly while BPDC has well acquisition performance. Therefore,for weak GPS signal acquisition,BPDC algorithm can acquire the signal with lower CNR and has better acquisition property.展开更多
Two types of lanthanide metal–organic frameworks(LnMOFs)[Zr_(16)-BPDC-Eu_(1−x)Tb_(x)]and[Zr_(16)-Eu_(1−x)Tb_(x)](x=0.17,0.25,0.5)were designed and constructed through the directed assembly of multi-hydroxyl/ketone Zr...Two types of lanthanide metal–organic frameworks(LnMOFs)[Zr_(16)-BPDC-Eu_(1−x)Tb_(x)]and[Zr_(16)-Eu_(1−x)Tb_(x)](x=0.17,0.25,0.5)were designed and constructed through the directed assembly of multi-hydroxyl/ketone Zr-oxo clusters and Ln^(3+)ions in a single-crystal-to-single-crystal(SCSC)structural transformation manner.展开更多
基金Supported by the Fundamental Research Fund for the Central University(1002-56XAA13016)
文摘It is difficult to achieve accurate acquisition of weak global positioning system( GPS) signals with traditional methods. A weak signal acquisition strategy based on block processing and differentially coherent( BPDC) is put forward after analyzing the advantages and disadvantages of coherent and non-coherent integration algorithms. Code phase parallel search of the pre-coherent integration is conducted by using fast Fourier transform( FFT),and the results are then differential coherent processed and block processed. BPDC method reduces computation cost compared with coherent and noncoherent( CNC) algorithm. The performance of the two algorithms is also compared based on simulated signals. The result shows that the noise suppression effect of BPDC algorithms is superior to that of traditional CNC algorithm,and the superiority of BPDC is more apparent with the reduction of carrier to noise ratio( CNR). In the case that the pre-coherent integration length is 4 ms and CNR is reduced to 28 dB-Hz,CNC algorithm cannot yet acquire signal correctly while BPDC has well acquisition performance. Therefore,for weak GPS signal acquisition,BPDC algorithm can acquire the signal with lower CNR and has better acquisition property.
基金supported financially by the NSFC of China(No.22175033).
文摘Two types of lanthanide metal–organic frameworks(LnMOFs)[Zr_(16)-BPDC-Eu_(1−x)Tb_(x)]and[Zr_(16)-Eu_(1−x)Tb_(x)](x=0.17,0.25,0.5)were designed and constructed through the directed assembly of multi-hydroxyl/ketone Zr-oxo clusters and Ln^(3+)ions in a single-crystal-to-single-crystal(SCSC)structural transformation manner.
